• Journal of the Korean Chemical Society
• /
• v.29 no.4
• /
• pp.426-436
• /
• 1985

Preparative and kinetic photochemical reactions of several benzanilides were studied. Several substituted benzanilides were synthesized by acylation of substituted anilines with substituted benzoyl chlorides. While benzanilide gave a photo-Fries type reaction product, 2-chlorobenzaniline, 2-bromobenzanilide, and 2-methoxybenzanilide gave a photocyclization reaction product, phenanthridone. Since 8-chlorophenanthridone was obtained from 2,2'-dichlorobenzanilide, the carbonyl phenyl is the excited site. Quantum yield of photocyclization of 2-chlorobenzanilide, 2'-chlorobenzanilide, and 2-methoxybenzanilide were obtained. 2-Chlorobenzanilide was photocyclized effectively and 2'-chlorobenzanilide ineffectively. Since the oxygen present in the reaction medium retarded the photocyclization reaction of 2-chlorobenzanilide, the triplet state of 2-chlorobenzanilide is involved. The mechanism of the photocyclization of 2-chlorobenzanilide is suggested: $\pi-complex$ between carbonyl phenyl and N-phenyl was formed from the triplet state of 2-chlorobenzanilide; neighbour phenyl (N-phenyl) assists for leaving of chlorine from carbonyl phenyl to make an intermediate, cyclized conjugated radical, because electron donating group on the N-phenyl ring accelerated the reaction; hydrogen detachment from the intermediate is obviously not a rate determined step because there was no isotope effect on the rate of photocyclization. The photocyclization reaction rate of 2-methoxybenzanilide was faster in the presence of oxygen than in the absence of oxygen. Thus, the singlet excited state of 2-methoxybenzanilide is involved in the reaction. Probably, the intermediate, methoxyhydro-phenanthridone is oxidized by oxygen in the medium to give phenanthridone.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2009.11a
• /
• pp.177-177
• /
• 2009

사용후 핵연료의 건식처리 시 핵연료 다발을 절단하여 voloxidation 즉 휘발산화처리를 하면 고온에 의해 분리가 가능한 핵분열생성물의 분리와 우라늄의 산화에 의한 부피팽창으로 핵연료가 쪼개져서 입도가 작아지고 또한 핵연료가 피복재에서 쉽게 박리되게 된다. 그 결과 폐기물 처리 시에 발열핵종으로 폐기물의 저준위화시에 분리가 요망되는 Cs-137이 분리되는 장점이 있어 습식 재처리에 있어서도 바람직하다. 건식처리에 있어서는 voloxidation 으로 처리된 피복재에는 금속 지르코늄에 불순물로 함유된 우라늄의 의한 방사화 생성물과 피복재 표변에 부착/침투한 방사화 생성물이 방사능을 갖게 된다. 이러한 부착된 TRU 잔류물은 통상 1% 미만으로 알파핵종의 방사능이 원자로에서 배출시에는 고준위 기준치의 약 100배 수준이었다가 30년 냉각후에는 약 1/10 수준으로 저준위화 된다. 지르코늄 금속중에 불순물로 함유된 우라늄의 방사화로 생기는 방사능은 고준위 기준치의 10% 를 넘지 않아서 피복재의 저준위화시에 고려할 필요가 없다. 발생열은 방출시에 고준위 기준치의 약 30 배 수준에서 5년 냉각후에는 기준치 미만이 되며 30년후에는 1/8000 정도로 저준위화 된다. 사용후 핵연료를 습시처리시에 발생하는 고준위 폐기물 중 약 1/4 가 피복재 (hull) 임을 고려하면 피복재의 저준위화는 사용후 연료의 건식처리에 있어서도 필수적인 과정이다. 특히 미국의 고준위 폐기물 처분장 Yucca Mt.의 포기와 우리의 고준위 폐기불 처분장이 공론화되는 싯점에서 저준위화는 매우 필요한 기술이다. 피복재는 방사성 물질의 침투두께가 0.01mm 미만이 대부분으로 저준위화에는 표면제염에 의한 저준위화가 주로 연구되어왔다. 표면제염에 의한 저준화는 이온 빔, laser에 의한 방법, dry ice 분사에 의한 방법이 시도되었다. 염소기체를 이용하여 지르코늄의 산화막을 제거하고자 하였으나 이 산화막이 안정적이어서 표변의 연마, 아크릴 칼의 사용, 표면을 눌러서 처리하는 등 전처리하여서 염소기체 반응에 의한 표면제거 실험이 가장 효과적임이 실험적 결과이었다. 이러한 전처리로 방사능을 1/100 수준으로 낮춘다고 하더라도 지르코늄 금속중에 불순물로 함유된 우라늄의 방사화에 의해 중저준위 폐기물의 범주에서 벗어나지 않으므로 재활용에는 제한이 있다. 또한 전처리(표면제염)하여 분리되는 고준위는 다른 고준위 염폐기물과 함께 처리하여 발열 핵종을 제거하면 중저준위화가 가능하다. 저준위화 된 hull폐기물에는 지르코늄 금속에 불순물로서 함유되어있는 우라늄에 의한 방사능을 갖는데 이들의 제거나 분리는 지르코늄 합금 피복재 원료물질에 불순물로 함유하는 우라늄의 함량을 낮추는 것과 유사한 문제이다. 현재까지 지르코늄합금 피복재에 우라늄이 불순물로 함유된 것을 사용함으로 원자로내에서 방사화되어서 방사능을 갖게 되는 것은 피할 수가 없다. 따라서 저준위화 처리된 피복재는 장기 보관으로 방사능을 감쇠시켜서 재활용하도록 한다. 처리 방법으로는 초고압 압축저장, 시멘트 고화, 합성암석에 의한 고화법 등으로 장기간 보관 후에 금속으로서 재활용한다.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.16 no.4
• /
• pp.18-24
• /
• 2012

In this study, hybrid method using polyvinyl acetate (PVAc) which has a strong adhesion and flexibility in which acrylic copolymer chemical-reaction reacts with cement, and is eco-friendly, is to improve the watertightness. The hybrid method is applied applied primarily waterproof stuff comprising silicate system and secondary mortar mixed with PVAc on the concrete surface. And then, in order to evaluate the performance, the properties of bond strength and amount of water absorption were measured. Based on the above experiments, mock-up specimens for field application were fabricated, and then the properties were evaluated as laboratory experiments. As the results, specimens cast from hybrid method using PVAc showed the best results on watertightness and bond strength. And also, with respect to experiment of mock-up specimens, the properties were in agreement with laboratory results. Especially, it could know that PVAc has strengthening effect from the results of the compressive strength. Due to outstanding results of carbonation depth and resistance to chloride ion penetration, it may be applied in weak areas such as underground and marine structures.

• Journal of Embryo Transfer
• /
• v.32 no.3
• /
• pp.235-241
• /
• 2017

To preserve genetic materials, cryopreservation of the semen from live animals is the main technique to establish cryo-banking system which could be used for artificial insemination and embryo transfer. However, the population of Korean black goat (KBG) becomes to dwindle in number and is now faced genetic erosion by crossbreeding with non-native breeds in small KBG farms. In this study, simple freezing method was used to preserve frozen semen from KBG using spermatozoa of cauda epididymis (CE) and electro-stimulated semen (ES). The negative effects of seminal plasma on fresh sperm was confirmed using precipitation test of Triladyl egg yolk diluent and sperm viability after thawing was compared between CE and ES spermatozoa. When seminal plasma of fresh ES semen was washed with semen washing media (SWM), the rates of live sperm shown no significant difference between CE and ES spermatozoa before freezing. However, the survival rate of frozen/thawed CE sperm was higher than ES ($74.6{\pm}10.6%$ vs $53.8{\pm}5.2%$) with significant difference (p < 0.05). The results of longevity test on frozen/thawed sperm from CE showed healthier sperm than ES. Therefore, spermatozoa from CE could be used for cryo-banking system in KBG lines. The more studies are needed to increase survival rate of ES semen.

• Journal of the Korean Applied Science and Technology
• /
• v.37 no.6
• /
• pp.1678-1686
• /
• 2020

This study attempted to derive the possibility of using wood pellet using rice husk, which is an agricultural byproduct, and tried to improve the lower calorific value of rice hulls thorough expansion technology and combustion additives. In the physical and chemical analysis of rice husk, the result was obtained that the chlorine content was 0.09%, which did not meet the wood pellet quality standard of Korea. When making rice hulls into expanded rice husk through the expansion technology, the chlorine content decreased, resulting in a product of 0.02%, which is equivalent to the wood pellet standard of Korea, and the calorific value was also increased to 4,280 kcal/kg compared to the existing 3,780 kcal/kg. To obtain a product of 5,000 kcal/kg or more, borax, hydrogen peroxide, and sodium hydroxide was used as combustion improver. However the improvement in calorific value was insufficient. After conversion to coffee oil path using coffee grounds, which is a waste resource biomass, it is mixed into an expanded rice husk, and when the product is analyzed, the coffee oil 15 wt% mixed product shows an excess of 4,949 kcal/kg. When using rice husk, an agricultural byproduct, as wood pellets, it is considered desirable to use waste resources to improve the calorific value, and according to the results of this study, when mixing coffee oil, rice husk can be sufficiently used as wooden pellets.

• Journal of Food Hygiene and Safety
• /
• v.37 no.4
• /
• pp.232-237
• /
• 2022

The present study investigated the bactericidal effects of chlorine dioxide (CD) and electrolyzed water (EW) on pathogenic bacteria, such as Bacillus cereus, Staphylococcus aureus, Salmonella Typhimurium, and Escherichia coli O157:H7, by treatment them with CD and EW, respectively, for 0, 2, 4, 6, 8, and 10 min. Additionally, the sensitivities of Gram-positive (B. cereus and S. aureus) and Gram-negative (S. Typhimurium and E. coli O157:H7) to CD and EW were compared, respectively. In CD, the D-values for B. cereus, S. aureus, S. Typhimurium, and E. coli O157:H7 were 1.85±0.64, 2.06±0.85, 2.26±0.89, and 2.59±0.40 min, respectively. In EW, the D-values for B. cereus, S. aureus, S. Typhimurium, and E. coli O157:H7 were 2.13±0.32, 1.64±0.64, 1.71±0.32, and 1.86±0.36 min, respectively. All strains decreased consistently for 10 min in both CD and EW. However, the D-values of each bacterial species did not differ significantly between CD and EW (P>0.05). When comparing the bactericidal effect of CD and EW, no difference in D-value was observed, even though the pH and available chlorine concentration of CD were significantly lower than those of EW. These data could be used for the application of CD and EW in the food industry, considering characteristics such as the selection of optimal disinfectants, determination of optimal concentrations, and sensitivity to disinfection targets.

• International Journal of Highway Engineering
• /
• v.12 no.2
• /
• pp.107-113
• /
• 2010

In this study, the relative effects of low-chloride deicier(LCD) and two other deicing agents on the scaling of concrete were conducted in a series of tests at laboratory accordance with the ASTM C 672. The solutions concentration of deicers tested included 1, 4, 10%. Tap water was used as control. The amount of scaling was evaluated gravimetrically. As test result of deicer solution types, when applied to 4% solutions, surface scaling of concrete after 56 freeze-thaw cycles was produced significantly as about 9 times on LCD solution, as about 18 times on $CaCl_2$ solution, and as about 33 times on NaCl solution comparing with tap water. As test result of deicer solution concentrations, relatively low concentrations (of the 4% by weight) of deicer were produced more surface scaling than higher concentrations (of the 10% by weight) or lower concentrations (of the 1% by weight) of deicer. It show that the damaging concentration is of the order of 3~4% for previous research result. It appears that the mechanism of surface scaling is primarily physical rather than chemical. Also, the effect of chloride deicier types, freeze-thaw cycling, and air contents on the performance of concrete was experimentally investigated. The results show that the concrete specimens subjected to freeze-thaw cycling scaled more severely in exposure to deicing salt than those in non-exposure to deicing salt, weight losses of the specimens tested in exposure to deicing salt were twice as much as those tested in non-exposure to deicing salt. Relative dynamic modulus of elasticity of concrete specimens decreased more quickly in exposure to deicing salt than in non-exposure to deicing salt. Also, relative dynamic modulus of elasticity of concrete specimens in exposure to sodium chloride deicing salt was decreased more quickly comparing with exposure to LCD salt. It is also shown that the chloride contents according to concrete specimen depths was more largely in exposure to LCD salt. When concrete specimen is exposed to chloride deicing salts and freeze-thaw cycling, performance degradation in the entrained air concrete(AE concrete) retarded more considerably comparing with non-entrained air concrete(Non-AE concrete).

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.9 no.4
• /
• pp.177-186
• /
• 2005

The latest concrete structure has showed that the deterioration of durability has been increased by the damage from salt, carbonization, freezing & thawing and the others. Therefore, the measures for the concrete which has deteriorated durability have been taken. Among them, it has been often used that surface treatment which cuts off the deterioration factors of durability by protecting the surface of concrete. However, troubles such as fracture and rupture in the repair layer have been reported as time goes by due to the difference between the organic repair material like epoxy and concrete properties. Researchers have been developing the repair material which can cut off the deterioration factors of durability such as $CO_2$ gas, chloride ion and water by making the formation of concrete elaborate through the reaction with calcium ion when the surface improving agent is coated on the concrete. The main ingredient of that is inorganic substance which is the same as the concrete property. This study was evaluated the surface improving agent for permeability, watertightness, air-permeability, chemical resistance and elution resistance. As a result, it has been reported that the surface improving agent improves watertightness and air-permeability by penetration more than 10mm within concrete. Therefore, it is concluded that the surface improving agent developed in this research prevents deterioration of concrete durability when it is coated on the concrete structure.

• Journal of Food Hygiene and Safety
• /
• v.28 no.3
• /
• pp.227-233
• /
• 2013

In this study, we evaluated the ability of various disinfectants to suppress the growth of microorganisms in fresh-cut products and organic vegetable. The growth of more than 50% of B. cereus isolates were suppressed by 50% ethanol, 0.1% hydrogen peroxide, 0.4% sodium hypochlorite or 1% calcium oxide. E. coli generally showed high susceptibility to concentration of 10% ethanol, 0.4% sodium hypochlorite and 1% calcium oxide. Eighty percent or more of S. aureus isolates exhibited resistance to ethanol, hydrogen peroxide and sodium hypochlorite, but the isolates were susceptible to concentrations of 1% calcium oxide. All isolates evaluated in this study were sensitive to benzalkonium chloride (BAC) and growth in the presence of $2.0{\mu}g/mL$ of BAC was completely inhibited. These pathogens showed widely different susceptibilities to different organic acids. Greater than 0.5% acetic acid and 2% and higher concentrations of malic acid and tartaric acid inhibited the growth of 60% of the isolates of B. cereus. Two percent acetic acid and tartaric acid inhibited 50% of the S. aureus isolates. Seventy percent of the E. coli isolates were resistant to malic acid and susceptible to 1% acetic acid and 10% tartaric acid. The antibacterial effects of the various sanitizers evaluated in this study were not only dependent on the type of disinfectant but also on the pathogen. Thus, it is important to select a sanitizer that is safe and effective at removing specific types of microorganisms.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.38 no.9
• /
• pp.1265-1270
• /
• 2009

Pathogens contaminated on the surface of utensils could contribute to the occurrence of outbreaks due to cross-contamination to foods during the food preparation process. Therefore, the efficacy of chemical sanitizers (chlorine-based and alcohol-based commercial sanitizers) and dry-heat ($71^{\circ}C$) on inhibiting biofilms of five foodborne pathogens (Escherichia coli O157:H7, Salmonella Typhimurium, Pseudomonas aeruginosa, Listeria monocytogenes, and Staphylococcus aureus) on the surface of stainless steel and polypropylene were investigated in this study. Initial populations of pathogens were 8.8$\sim$9.3 and 9.4$\sim$10.3 log CFU/coupon on the surface of stainless steel and polypropylene coupon, respectively, and these populations were not significantly reduced when they were treated with water for 5 min at room temperature. Treatments with chlorine sanitizer and dry-heat were not effective on inactivating pathogens on the surfaces of stainless steel and polypropylene. In contrast, treatments with alcohol sanitizer were very effective on inactivating pathogens on the surfaced of stainless steel and polypropylene. Reduction levels ranged from 3.4 to 6.4 log and from 5.5 to 7.4 log CFU/coupon in stainless steel and plastic coupons, respectively. From these results, alcohol-based sanitizer could be used as a potential way for controlling microbial contamination on the surface of utensils, cooking equipment, and other related environments.